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The Northern short-tailed shrew is a small, energetic mammal that lives in central and eastern North America. The Mexican beaded lizard is a much larger reptile found in Mexico and Guatemala. These species are separated by a lot of a land and several million years of evolution, yet they share astonishing similarities. Not only are they both venomous, but the toxic proteins in their saliva have evolved in very similar ways from a common ancestor, converging on parallel lethal structures independently of one other.
This discovery, from Yael Aminetzach at Harvard University, shows that adaptations are sometimes very predictable. Despite the many changes that could have shaped the course of venom proteins in lizards and shrews, they seem to have gone down a consistent and similar route.
Northern short-tailed shrew by Giles Gonthier; Mexican beaded lizard by PiccoloNamek
The northern short-tailed shrew is one of the few venomous mammals, but its poisonous bite is painful to humans and can kill smaller animals. The key to its venom is a protein called BLTX, whose job is to cut another protein in...
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